1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * SR-IPv6 implementation 4 * 5 * Author: 6 * David Lebrun <david.lebrun@uclouvain.be> 7 */ 8 9 #include <linux/types.h> 10 #include <linux/skbuff.h> 11 #include <linux/net.h> 12 #include <linux/module.h> 13 #include <net/ip.h> 14 #include <net/ip_tunnels.h> 15 #include <net/lwtunnel.h> 16 #include <net/netevent.h> 17 #include <net/netns/generic.h> 18 #include <net/ip6_fib.h> 19 #include <net/route.h> 20 #include <net/seg6.h> 21 #include <linux/seg6.h> 22 #include <linux/seg6_iptunnel.h> 23 #include <net/addrconf.h> 24 #include <net/ip6_route.h> 25 #include <net/dst_cache.h> 26 #ifdef CONFIG_IPV6_SEG6_HMAC 27 #include <net/seg6_hmac.h> 28 #endif 29 30 struct seg6_lwt { 31 struct dst_cache cache; 32 struct seg6_iptunnel_encap tuninfo[0]; 33 }; 34 35 static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt) 36 { 37 return (struct seg6_lwt *)lwt->data; 38 } 39 40 static inline struct seg6_iptunnel_encap * 41 seg6_encap_lwtunnel(struct lwtunnel_state *lwt) 42 { 43 return seg6_lwt_lwtunnel(lwt)->tuninfo; 44 } 45 46 static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = { 47 [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY }, 48 }; 49 50 static int nla_put_srh(struct sk_buff *skb, int attrtype, 51 struct seg6_iptunnel_encap *tuninfo) 52 { 53 struct seg6_iptunnel_encap *data; 54 struct nlattr *nla; 55 int len; 56 57 len = SEG6_IPTUN_ENCAP_SIZE(tuninfo); 58 59 nla = nla_reserve(skb, attrtype, len); 60 if (!nla) 61 return -EMSGSIZE; 62 63 data = nla_data(nla); 64 memcpy(data, tuninfo, len); 65 66 return 0; 67 } 68 69 static void set_tun_src(struct net *net, struct net_device *dev, 70 struct in6_addr *daddr, struct in6_addr *saddr) 71 { 72 struct seg6_pernet_data *sdata = seg6_pernet(net); 73 struct in6_addr *tun_src; 74 75 rcu_read_lock(); 76 77 tun_src = rcu_dereference(sdata->tun_src); 78 79 if (!ipv6_addr_any(tun_src)) { 80 memcpy(saddr, tun_src, sizeof(struct in6_addr)); 81 } else { 82 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC, 83 saddr); 84 } 85 86 rcu_read_unlock(); 87 } 88 89 /* Compute flowlabel for outer IPv6 header */ 90 static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb, 91 struct ipv6hdr *inner_hdr) 92 { 93 int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel; 94 __be32 flowlabel = 0; 95 u32 hash; 96 97 if (do_flowlabel > 0) { 98 hash = skb_get_hash(skb); 99 hash = rol32(hash, 16); 100 flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK; 101 } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) { 102 flowlabel = ip6_flowlabel(inner_hdr); 103 } 104 return flowlabel; 105 } 106 107 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */ 108 int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto) 109 { 110 struct dst_entry *dst = skb_dst(skb); 111 struct net *net = dev_net(dst->dev); 112 struct ipv6hdr *hdr, *inner_hdr; 113 struct ipv6_sr_hdr *isrh; 114 int hdrlen, tot_len, err; 115 __be32 flowlabel; 116 117 hdrlen = (osrh->hdrlen + 1) << 3; 118 tot_len = hdrlen + sizeof(*hdr); 119 120 err = skb_cow_head(skb, tot_len + skb->mac_len); 121 if (unlikely(err)) 122 return err; 123 124 inner_hdr = ipv6_hdr(skb); 125 flowlabel = seg6_make_flowlabel(net, skb, inner_hdr); 126 127 skb_push(skb, tot_len); 128 skb_reset_network_header(skb); 129 skb_mac_header_rebuild(skb); 130 hdr = ipv6_hdr(skb); 131 132 /* inherit tc, flowlabel and hlim 133 * hlim will be decremented in ip6_forward() afterwards and 134 * decapsulation will overwrite inner hlim with outer hlim 135 */ 136 137 if (skb->protocol == htons(ETH_P_IPV6)) { 138 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)), 139 flowlabel); 140 hdr->hop_limit = inner_hdr->hop_limit; 141 } else { 142 ip6_flow_hdr(hdr, 0, flowlabel); 143 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb)); 144 145 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); 146 } 147 148 hdr->nexthdr = NEXTHDR_ROUTING; 149 150 isrh = (void *)hdr + sizeof(*hdr); 151 memcpy(isrh, osrh, hdrlen); 152 153 isrh->nexthdr = proto; 154 155 hdr->daddr = isrh->segments[isrh->first_segment]; 156 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); 157 158 #ifdef CONFIG_IPV6_SEG6_HMAC 159 if (sr_has_hmac(isrh)) { 160 err = seg6_push_hmac(net, &hdr->saddr, isrh); 161 if (unlikely(err)) 162 return err; 163 } 164 #endif 165 166 skb_postpush_rcsum(skb, hdr, tot_len); 167 168 return 0; 169 } 170 EXPORT_SYMBOL_GPL(seg6_do_srh_encap); 171 172 /* insert an SRH within an IPv6 packet, just after the IPv6 header */ 173 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) 174 { 175 struct ipv6hdr *hdr, *oldhdr; 176 struct ipv6_sr_hdr *isrh; 177 int hdrlen, err; 178 179 hdrlen = (osrh->hdrlen + 1) << 3; 180 181 err = skb_cow_head(skb, hdrlen + skb->mac_len); 182 if (unlikely(err)) 183 return err; 184 185 oldhdr = ipv6_hdr(skb); 186 187 skb_pull(skb, sizeof(struct ipv6hdr)); 188 skb_postpull_rcsum(skb, skb_network_header(skb), 189 sizeof(struct ipv6hdr)); 190 191 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen); 192 skb_reset_network_header(skb); 193 skb_mac_header_rebuild(skb); 194 195 hdr = ipv6_hdr(skb); 196 197 memmove(hdr, oldhdr, sizeof(*hdr)); 198 199 isrh = (void *)hdr + sizeof(*hdr); 200 memcpy(isrh, osrh, hdrlen); 201 202 isrh->nexthdr = hdr->nexthdr; 203 hdr->nexthdr = NEXTHDR_ROUTING; 204 205 isrh->segments[0] = hdr->daddr; 206 hdr->daddr = isrh->segments[isrh->first_segment]; 207 208 #ifdef CONFIG_IPV6_SEG6_HMAC 209 if (sr_has_hmac(isrh)) { 210 struct net *net = dev_net(skb_dst(skb)->dev); 211 212 err = seg6_push_hmac(net, &hdr->saddr, isrh); 213 if (unlikely(err)) 214 return err; 215 } 216 #endif 217 218 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen); 219 220 return 0; 221 } 222 EXPORT_SYMBOL_GPL(seg6_do_srh_inline); 223 224 static int seg6_do_srh(struct sk_buff *skb) 225 { 226 struct dst_entry *dst = skb_dst(skb); 227 struct seg6_iptunnel_encap *tinfo; 228 int proto, err = 0; 229 230 tinfo = seg6_encap_lwtunnel(dst->lwtstate); 231 232 switch (tinfo->mode) { 233 case SEG6_IPTUN_MODE_INLINE: 234 if (skb->protocol != htons(ETH_P_IPV6)) 235 return -EINVAL; 236 237 err = seg6_do_srh_inline(skb, tinfo->srh); 238 if (err) 239 return err; 240 break; 241 case SEG6_IPTUN_MODE_ENCAP: 242 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6); 243 if (err) 244 return err; 245 246 if (skb->protocol == htons(ETH_P_IPV6)) 247 proto = IPPROTO_IPV6; 248 else if (skb->protocol == htons(ETH_P_IP)) 249 proto = IPPROTO_IPIP; 250 else 251 return -EINVAL; 252 253 err = seg6_do_srh_encap(skb, tinfo->srh, proto); 254 if (err) 255 return err; 256 257 skb_set_inner_transport_header(skb, skb_transport_offset(skb)); 258 skb_set_inner_protocol(skb, skb->protocol); 259 skb->protocol = htons(ETH_P_IPV6); 260 break; 261 case SEG6_IPTUN_MODE_L2ENCAP: 262 if (!skb_mac_header_was_set(skb)) 263 return -EINVAL; 264 265 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0) 266 return -ENOMEM; 267 268 skb_mac_header_rebuild(skb); 269 skb_push(skb, skb->mac_len); 270 271 err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE); 272 if (err) 273 return err; 274 275 skb->protocol = htons(ETH_P_IPV6); 276 break; 277 } 278 279 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 280 skb_set_transport_header(skb, sizeof(struct ipv6hdr)); 281 282 return 0; 283 } 284 285 static int seg6_input(struct sk_buff *skb) 286 { 287 struct dst_entry *orig_dst = skb_dst(skb); 288 struct dst_entry *dst = NULL; 289 struct seg6_lwt *slwt; 290 int err; 291 292 err = seg6_do_srh(skb); 293 if (unlikely(err)) { 294 kfree_skb(skb); 295 return err; 296 } 297 298 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 299 300 preempt_disable(); 301 dst = dst_cache_get(&slwt->cache); 302 preempt_enable(); 303 304 skb_dst_drop(skb); 305 306 if (!dst) { 307 ip6_route_input(skb); 308 dst = skb_dst(skb); 309 if (!dst->error) { 310 preempt_disable(); 311 dst_cache_set_ip6(&slwt->cache, dst, 312 &ipv6_hdr(skb)->saddr); 313 preempt_enable(); 314 } 315 } else { 316 skb_dst_set(skb, dst); 317 } 318 319 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 320 if (unlikely(err)) 321 return err; 322 323 return dst_input(skb); 324 } 325 326 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 327 { 328 struct dst_entry *orig_dst = skb_dst(skb); 329 struct dst_entry *dst = NULL; 330 struct seg6_lwt *slwt; 331 int err = -EINVAL; 332 333 err = seg6_do_srh(skb); 334 if (unlikely(err)) 335 goto drop; 336 337 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 338 339 preempt_disable(); 340 dst = dst_cache_get(&slwt->cache); 341 preempt_enable(); 342 343 if (unlikely(!dst)) { 344 struct ipv6hdr *hdr = ipv6_hdr(skb); 345 struct flowi6 fl6; 346 347 memset(&fl6, 0, sizeof(fl6)); 348 fl6.daddr = hdr->daddr; 349 fl6.saddr = hdr->saddr; 350 fl6.flowlabel = ip6_flowinfo(hdr); 351 fl6.flowi6_mark = skb->mark; 352 fl6.flowi6_proto = hdr->nexthdr; 353 354 dst = ip6_route_output(net, NULL, &fl6); 355 if (dst->error) { 356 err = dst->error; 357 dst_release(dst); 358 goto drop; 359 } 360 361 preempt_disable(); 362 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); 363 preempt_enable(); 364 } 365 366 skb_dst_drop(skb); 367 skb_dst_set(skb, dst); 368 369 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 370 if (unlikely(err)) 371 goto drop; 372 373 return dst_output(net, sk, skb); 374 drop: 375 kfree_skb(skb); 376 return err; 377 } 378 379 static int seg6_build_state(struct nlattr *nla, 380 unsigned int family, const void *cfg, 381 struct lwtunnel_state **ts, 382 struct netlink_ext_ack *extack) 383 { 384 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1]; 385 struct seg6_iptunnel_encap *tuninfo; 386 struct lwtunnel_state *newts; 387 int tuninfo_len, min_size; 388 struct seg6_lwt *slwt; 389 int err; 390 391 if (family != AF_INET && family != AF_INET6) 392 return -EINVAL; 393 394 err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla, 395 seg6_iptunnel_policy, extack); 396 397 if (err < 0) 398 return err; 399 400 if (!tb[SEG6_IPTUNNEL_SRH]) 401 return -EINVAL; 402 403 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]); 404 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]); 405 406 /* tuninfo must contain at least the iptunnel encap structure, 407 * the SRH and one segment 408 */ 409 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) + 410 sizeof(struct in6_addr); 411 if (tuninfo_len < min_size) 412 return -EINVAL; 413 414 switch (tuninfo->mode) { 415 case SEG6_IPTUN_MODE_INLINE: 416 if (family != AF_INET6) 417 return -EINVAL; 418 419 break; 420 case SEG6_IPTUN_MODE_ENCAP: 421 break; 422 case SEG6_IPTUN_MODE_L2ENCAP: 423 break; 424 default: 425 return -EINVAL; 426 } 427 428 /* verify that SRH is consistent */ 429 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo))) 430 return -EINVAL; 431 432 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt)); 433 if (!newts) 434 return -ENOMEM; 435 436 slwt = seg6_lwt_lwtunnel(newts); 437 438 err = dst_cache_init(&slwt->cache, GFP_ATOMIC); 439 if (err) { 440 kfree(newts); 441 return err; 442 } 443 444 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len); 445 446 newts->type = LWTUNNEL_ENCAP_SEG6; 447 newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT; 448 449 if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) 450 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; 451 452 newts->headroom = seg6_lwt_headroom(tuninfo); 453 454 *ts = newts; 455 456 return 0; 457 } 458 459 static void seg6_destroy_state(struct lwtunnel_state *lwt) 460 { 461 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache); 462 } 463 464 static int seg6_fill_encap_info(struct sk_buff *skb, 465 struct lwtunnel_state *lwtstate) 466 { 467 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 468 469 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo)) 470 return -EMSGSIZE; 471 472 return 0; 473 } 474 475 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate) 476 { 477 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 478 479 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo)); 480 } 481 482 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 483 { 484 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a); 485 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b); 486 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr); 487 488 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr)) 489 return 1; 490 491 return memcmp(a_hdr, b_hdr, len); 492 } 493 494 static const struct lwtunnel_encap_ops seg6_iptun_ops = { 495 .build_state = seg6_build_state, 496 .destroy_state = seg6_destroy_state, 497 .output = seg6_output, 498 .input = seg6_input, 499 .fill_encap = seg6_fill_encap_info, 500 .get_encap_size = seg6_encap_nlsize, 501 .cmp_encap = seg6_encap_cmp, 502 .owner = THIS_MODULE, 503 }; 504 505 int __init seg6_iptunnel_init(void) 506 { 507 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 508 } 509 510 void seg6_iptunnel_exit(void) 511 { 512 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 513 } 514